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pjulian avatar image
pjulian asked

Smartsolar 150/100 solar watts low

Hi all,

I have read some other posts from people when searching for more information, however they seem to be a bit different to what I am seeing.

I have just installed a Smartsolar 150/100 with 2.5kw of panels connected and a 24V wet cell battery bank.

I have also installed a BMV-712 between batteries and charger so that I can get some rough indication of SOC.

In a totally sunny day where everything should be working fine, the watts coming from the panels is a lot lower than I was used to seeing on the old charge controller, sometimes only around 350w is showing on the solar input section.

The charger is charging the batteries and I can see that it's doing this, and it's sitting in BULK mode.

Other posts I have read have cited the same problem with low wattage from the solar, but when the people check their charger it is actually in FLOAT mode, my charger isn't getting to this mode but seems to be reducing the input from the solar like it seems to do in FLOAT mode.

In checking the history it has actually reached absorption and float mode on a few occasions, but not many, it really should be hitting it every day with the panel capacity, sunlight and battery capacity. Typically I am using about 65 a/h of power a night, this should be replenished pretty quickly realistically with this setup.

I have triple checked settings, connections, everything seems correct.

When I run a load like the microwave or something from the inverter the watts coming from the panels jumps up to more like it should be, so it's like the charger is limiting the charge to the batteries and therefore limiting the wattage it is accepting from the panels.

I have played around with the charge current, it should be around 45A for my battery setup, I have increased it and decreased it but I have never seen the charge current get to more than about 16A according to the controller.

Any thoughts as to what might be going on ?

Thanks for your help.

smart solar charging behaviour
4 comments
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klim8skeptic avatar image klim8skeptic ♦ commented ·

How do you have your array wired up?

What is the array's voltage reading at the Mppt?

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pjulian avatar image pjulian klim8skeptic ♦ commented ·

I have 18 x 170w panels, wired in 6 groups of 3 panels wired in series to get around 120V, then those groups of 3 panels are broken into 2 groups connected in parallel to keep the voltage under control but get a bit more current flowing.

The voltage at the controller is showing correctly at around 120, obviously that fluctuates up and down a little, but average would be around 120.

The voltage on the battery side is also showing correctly, around 29V when charging.

Thanks

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klim8skeptic avatar image klim8skeptic ♦ pjulian commented ·

The array voltages seem right.

Checked the array fusing to see if any strings are oc?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

Some screenshots of VictronConnect could help.

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2 Answers
Paul B avatar image
Paul B answered ·

When the Battery voltage reaches 29volts then the MPPT unit will reduce the amps/watts and this is the correct operation, even if you are in bulk mode, this is because the battery is FULL and the battery does not need them amps anymore. once it changes to float the voltage will then slowly reduce to the float level and during that period there will be zero amps, once float voltage is reach then the amps will again increase to what the battery needs plus any conected loads. (this will depend on the panels output as well)

when you turn on a load the voltage drops and thus the MPPT supplies more power from the panels for that time period


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pjulian avatar image
pjulian answered ·

Thanks Paul, I thought this was what was happening.

Why though would it still show bulk mode though if it was really in float or should be in float ?

How long would you expect that it would sit like this before it actually tells you it's changed modes ?

That seems like a strange behaviour and is confusing as well.

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